There is a lot of concern about food waste and it may be due to leftovers that never get used but it probably isn't the bulk of Americans - 92 percent of people eat everything. Obviously that can be bad for people in other ways if people put a lot on their plate.

Wansink and co-author Katherine Abowd Johnson analyzed 1179 diners and concluded that we're a Clean Plate Planet. Although diners were analyzed in 8 developed countries, the US, Canada, France, Taiwan, Korea, Finland, and the Netherlands, the results were nearly identical. If we serve it, we'll eat it regardless of gender or nationality. "Part of why we finish most of what we serve is because we are aware enough to know how much we'll want in the first place," says Johnson.

Credit: Daniel Miller

The finding did not hold true with children. Analysis of 326 participants under 18 years old, showed that the average child eats only 59% of what he or she serves. "This might be because kids are less certain about whether they will like a particular food," says Wansink. "Regardless, this is good news for parents who are frustrated that their kids don't clean their plate. It appears few of them do."

Wansink says that these findings, published in the International Journal of Obesity, can positively impact an individual's eating behavior, "Just knowing that you're likely to consume almost all of what you serve yourself can help you be more mindful of appropriate portion size." Next time you grab that serving spoon, think to yourself, "How much do I want to eat?" and serve accordingly.